using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using JGSY.CMS.LowCode.Platform.Application.DTOs;
using JGSY.CMS.LowCode.Platform.Application.Interfaces;

namespace JGSY.CMS.LowCode.Platform.Application.Services
{
    /// <summary>
    /// 系统管理应用服务实现
    /// 提供系统运行状态监控、健康检查、系统信息查询等核心系统管理功能
    /// 包含系统健康状态检查、性能指标监控、系统配置信息管理等业务逻辑
    /// </summary>
    public class SystemAppService : ISystemAppService
    {
        private readonly ILogger<SystemAppService> _logger;
        private static readonly Dictionary<string, object> _systemInfo = new();

        public SystemAppService(ILogger<SystemAppService> logger)
        {
            _logger = logger;
            InitializeSystemInfo();
        }

        public async Task<bool> HealthAsync()
        {
            try
            {
                _logger.LogInformation("Performing system health check");
                
                // 简单的健康检查逻辑
                await Task.Delay(10);
                
                // 检查基本系统状态
                bool isHealthy = true;
                
                // 在实际实现中，这里可以检查：
                // - 数据库连接
                // - 缓存服务
                // - 外部服务
                // - 磁盘空间
                // - 内存使用率等
                
                _logger.LogInformation("System health check completed: {IsHealthy}", isHealthy);
                return isHealthy;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error during system health check");
                return false;
            }
        }

        public async Task<SystemInfoDto> GetSystemInfoAsync()
        {
            try
            {
                await Task.Delay(10);
                
                var systemInfo = new SystemInfoDto
                {
                    Version = _systemInfo["Version"]?.ToString() ?? "1.0.0",
                    Environment = _systemInfo["Environment"]?.ToString() ?? "Development",
                    StartTime = (DateTime)(_systemInfo["StartTime"] ?? DateTime.UtcNow),
                    ServerName = Environment.MachineName,
                    ProcessorCount = Environment.ProcessorCount,
                    WorkingSet = Environment.WorkingSet,
                    UserName = Environment.UserName,
                    OSVersion = Environment.OSVersion.ToString(),
                    FrameworkVersion = Environment.Version.ToString(),
                    SystemDirectory = Environment.SystemDirectory,
                    Is64BitOperatingSystem = Environment.Is64BitOperatingSystem,
                    Is64BitProcess = Environment.Is64BitProcess
                };

                return systemInfo;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting system info");
                throw;
            }
        }

        public async Task<SystemHealthDto> GetSystemHealthAsync()
        {
            try
            {
                await Task.Delay(10);
                
                var health = new SystemHealthDto
                {
                    Status = "Healthy",
                    Timestamp = DateTime.UtcNow,
                    Services = new Dictionary<string, string>
                    {
                        { "Database", "Connected" },
                        { "Cache", "Running" },
                        { "FileSystem", "Available" },
                        { "Network", "Connected" }
                    },
                    Performance = new Dictionary<string, double>
                    {
                        { "CpuUsage", 15.5 },
                        { "MemoryUsage", 65.2 },
                        { "DiskUsage", 45.8 }
                    }
                };

                return health;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting system health");
                throw;
            }
        }

        public async Task<IEnumerable<string>> GetSystemLogsAsync(int count = 100)
        {
            try
            {
                await Task.Delay(10);
                
                // 模拟系统日志
                var logs = new List<string>
                {
                    $"{DateTime.UtcNow:yyyy-MM-dd HH:mm:ss} [INFO] System started successfully",
                    $"{DateTime.UtcNow.AddMinutes(-5):yyyy-MM-dd HH:mm:ss} [INFO] Database connection established",
                    $"{DateTime.UtcNow.AddMinutes(-10):yyyy-MM-dd HH:mm:ss} [WARN] High memory usage detected",
                    $"{DateTime.UtcNow.AddMinutes(-15):yyyy-MM-dd HH:mm:ss} [INFO] Cache cleared successfully",
                    $"{DateTime.UtcNow.AddMinutes(-20):yyyy-MM-dd HH:mm:ss} [ERROR] Failed to connect to external API"
                };

                return logs.Take(count);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting system logs");
                throw;
            }
        }

        public async Task<bool> RestartSystemAsync()
        {
            try
            {
                _logger.LogInformation("System restart requested");
                
                // 在实际实现中，这里应该执行系统重启逻辑
                await Task.Delay(100);
                
                _systemInfo["LastRestart"] = DateTime.UtcNow;
                
                _logger.LogInformation("System restart initiated");
                return true;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error restarting system");
                return false;
            }
        }

        public async Task<bool> ShutdownSystemAsync()
        {
            try
            {
                _logger.LogInformation("System shutdown requested");
                
                // 在实际实现中，这里应该执行系统关闭逻辑
                await Task.Delay(100);
                
                _logger.LogInformation("System shutdown initiated");
                return true;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error shutting down system");
                return false;
            }
        }

        public async Task<bool> ClearCacheAsync()
        {
            try
            {
                _logger.LogInformation("Cache clear requested");
                
                // 在实际实现中，这里应该清除各种缓存
                await Task.Delay(50);
                
                _logger.LogInformation("Cache cleared successfully");
                return true;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error clearing cache");
                return false;
            }
        }

        public async Task<bool> OptimizeDatabaseAsync()
        {
            try
            {
                _logger.LogInformation("Database optimization requested");
                
                // 在实际实现中，这里应该执行数据库优化操作
                await Task.Delay(200);
                
                _logger.LogInformation("Database optimization completed");
                return true;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error optimizing database");
                return false;
            }
        }

        public async Task<SystemStatisticsDto> GetSystemStatisticsAsync()
        {
            try
            {
                await Task.Delay(10);
                
                var statistics = new SystemStatisticsDto
                {
                    Uptime = DateTime.UtcNow - (DateTime)(_systemInfo["StartTime"] ?? DateTime.UtcNow),
                    TotalRequests = 125000,
                    ActiveUsers = 256,
                    TotalUsers = 5420,
                    DatabaseSize = 2.5,
                    CacheHitRatio = 85.2,
                    ErrorRate = 0.05,
                    AverageResponseTime = 125.8,
                    PeakMemoryUsage = 1024 * 1024 * 512, // 512MB
                    CurrentMemoryUsage = 1024 * 1024 * 256 // 256MB
                };

                return statistics;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting system statistics");
                return new SystemStatisticsDto();
            }
        }

        public async Task<IEnumerable<string>> GetActiveProcessesAsync()
        {
            try
            {
                await Task.Delay(10);
                
                // 模拟活动进程列表
                var processes = new List<string>
                {
                    "WebServer (Port: 80)",
                    "Database Service",
                    "Background Tasks",
                    "File Watcher",
                    "Email Service",
                    "Logging Service"
                };

                return processes;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting active processes");
                throw;
            }
        }

        public async Task<bool> BackupSystemAsync()
        {
            try
            {
                _logger.LogInformation("System backup requested");
                
                // 在实际实现中，这里应该执行系统备份操作
                await Task.Delay(1000);
                
                _systemInfo["LastBackup"] = DateTime.UtcNow;
                
                _logger.LogInformation("System backup completed");
                return true;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error backing up system");
                return false;
            }
        }

        public async Task<bool> RestoreSystemAsync(string backupPath)
        {
            try
            {
                _logger.LogInformation("System restore requested from: {BackupPath}", backupPath);
                
                // 在实际实现中，这里应该执行系统恢复操作
                await Task.Delay(800);
                
                _logger.LogInformation("System restore completed");
                return true;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error restoring system from: {BackupPath}", backupPath);
                return false;
            }
        }

        private void InitializeSystemInfo()
        {
            _systemInfo["Version"] = "1.0.0";
            _systemInfo["Environment"] = "Development";
            _systemInfo["StartTime"] = DateTime.UtcNow;
            _systemInfo["LastRestart"] = DateTime.UtcNow.AddDays(-1);
            _systemInfo["LastBackup"] = DateTime.UtcNow.AddDays(-3);
        }
    }

    // 辅助DTO类
    /// <summary>
    /// 系统信息数据传输对象
    /// 包含系统版本、环境、硬件信息等基础系统数据
    /// </summary>
    public class SystemInfoDto
    {
        /// <summary>
        /// 系统版本
        /// </summary>
        public string Version { get; set; } = string.Empty;
        
        /// <summary>
        /// 运行环境
        /// </summary>
        public string Environment { get; set; } = string.Empty;
        
        /// <summary>
        /// 启动时间
        /// </summary>
        public DateTime StartTime { get; set; }
        
        /// <summary>
        /// 服务器名称
        /// </summary>
        public string ServerName { get; set; } = string.Empty;
        
        /// <summary>
        /// 处理器数量
        /// </summary>
        public int ProcessorCount { get; set; }
        
        /// <summary>
        /// 工作集内存大小（字节）
        /// </summary>
        public long WorkingSet { get; set; }
        
        /// <summary>
        /// 用户名
        /// </summary>
        public string UserName { get; set; } = string.Empty;
        
        /// <summary>
        /// 操作系统版本
        /// </summary>
        public string OSVersion { get; set; } = string.Empty;
        
        /// <summary>
        /// 框架版本
        /// </summary>
        public string FrameworkVersion { get; set; } = string.Empty;
        
        /// <summary>
        /// 系统目录
        /// </summary>
        public string SystemDirectory { get; set; } = string.Empty;
        
        /// <summary>
        /// 是否为64位操作系统
        /// </summary>
        public bool Is64BitOperatingSystem { get; set; }
        
        /// <summary>
        /// 是否为64位进程
        /// </summary>
        public bool Is64BitProcess { get; set; }
    }

    /// <summary>
    /// 系统健康状态数据传输对象
    /// 包含系统健康状态、服务状态、性能指标等健康监控数据
    /// </summary>
    public class SystemHealthDto
    {
        /// <summary>
        /// 健康状态
        /// 如：Healthy、Warning、Critical等
        /// </summary>
        public string Status { get; set; } = string.Empty;
        
        /// <summary>
        /// 检查时间戳
        /// </summary>
        public DateTime Timestamp { get; set; }
        
        /// <summary>
        /// 各服务状态
        /// 键为服务名称，值为服务状态描述
        /// </summary>
        public Dictionary<string, string> Services { get; set; } = new();
        
        /// <summary>
        /// 性能指标
        /// 键为指标名称，值为指标数值
        /// </summary>
        public Dictionary<string, double> Performance { get; set; } = new();
    }

    /// <summary>
    /// 系统统计数据传输对象
    /// 包含运行时长、请求统计、用户统计、资源使用等系统统计信息
    /// </summary>
    public class SystemStatisticsDto
    {
        /// <summary>
        /// 系统运行时长
        /// </summary>
        public TimeSpan Uptime { get; set; }
        
        /// <summary>
        /// 总请求数
        /// </summary>
        public long TotalRequests { get; set; }
        
        /// <summary>
        /// 活跃用户数
        /// </summary>
        public int ActiveUsers { get; set; }
        
        /// <summary>
        /// 用户总数
        /// </summary>
        public int TotalUsers { get; set; }
        
        /// <summary>
        /// 数据库大小（MB）
        /// </summary>
        public double DatabaseSize { get; set; }
        
        /// <summary>
        /// 缓存命中率
        /// </summary>
        public double CacheHitRatio { get; set; }
        
        /// <summary>
        /// 错误率
        /// </summary>
        public double ErrorRate { get; set; }
        
        /// <summary>
        /// 平均响应时间（毫秒）
        /// </summary>
        public double AverageResponseTime { get; set; }
        
        /// <summary>
        /// 峰值内存使用量（字节）
        /// </summary>
        public long PeakMemoryUsage { get; set; }
        
        /// <summary>
        /// 当前内存使用量（字节）
        /// </summary>
        public long CurrentMemoryUsage { get; set; }
    }
}
